What if f(5) if f(1) = 3.2 and f(x+1) = 5/2 (f(x))

Two customers went to a post office. first customer paid $12 for 14 and 5 envelopes the second paid 24.80 for 10 postcards and 15 envelopes. what is cost of each envelope?

Consider the input and output values for f(x) = 2x - 3 and g(x) = 2x + 7. what is a reasonable explanation for different rules with different input values producing the same sequence?

What is the equation of a line that passes through points (0, 4) and (-4,-8)?